1. Field of the Invention
This invention relates to dermal uses of non-irritating retinoids and particularly to dermal uses of the esters and amides of certain stereoisomers of retinoic acid.
2. Description of the Prior Art
Chronic sun exposure has been determined to create a number of skin disorders including skin cancer which is usually discernible by the presence of lesions known as keratoses as well as photoaging (or "dermatoheliosis") of the skin which is characterized by wrinkling, sallowness, roughness and mottled pigmentation. In a recent article entitled, "Topical Tretinoin Improves Photoaged Skin," JAMA 259, vol.4, pgs. 527-532, Jan. 22/29, 1988, the authors Webb et al. report that photoaging of the skin of middle-aged and elderly Caucasians could be improved within a 16-week period by daily topical application of a cream containing 0.1% tretinoin (all-trans-retinoic acid).
A side effect reported in the article which complicates the administration of tretinoin, is that the therapy is irritating to the skin and induces dermatitis of several weeks duration in almost all of the subjects undergoing the tretinoin therapy. Redness, peeling, stinging, burning and dryness were consistently experienced by nearly all subjects. Eleven of fifteen subjects experienced dermatitis severe enough to require the use of topical steroids to control the dermatitis. Three of fifteen withdrew from the tretinoin therapy due to the severity of the tretinoin-induced dermatitis. Also positive effects on the histology of the epidermal and stratum corneum layers of the dorsal forearm skin were noted in the tretinoin treated areas. Because of these side effects, recommendation for use of the therapy is inhibited and is not used to full advantage. A method of dermal therapy that would retain the effectiveness of tretinoin but which would be essentially non-irritating would provide a much needed solution to the treatment of photoaging. Further, non-irritating effective treatment of other skin disorders such as skin cancer would meet a long felt need in dermal therapy.